From the A40 in St Clears, the A477 is a trunk road with primary status as far as the Waterloo roundabout in Pembroke Dock, on the southeast side of the Milford Haven Waterway.

Responsibility for the management and maintenance of this section lies with the South Wales Trunk Road Agent on behalf of the Welsh Government.

[3] The full route was completed in 1839, running from St Clears via Llanddowror, Red Roses, Llanteg, Begelly and Carew to Pembroke Dock.

[7] A new bypass improvement scheme for the section of the A477 between St Clears and Red Roses was approved by the Welsh Government on 27 January 2012.

The A477, 28 miles (45 km) in length, runs from east to west, either through, near or over: The Cleddau Bridge was funded by tolls which are collected at Pembroke Dock from traffic in both directions.

[12] A review was carried out in early 2016, when Pembrokeshire County Councillors voted that all toll charges would remain unchanged and would not be abolished.